FixVault

Circuit/System Testing

WARNING: This page is about a different car, the 2008 GMC Sierra, 2008 GMC Cab & Chassis Sierra, 2008 Chevrolet Silverado, and 2008 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF. Disconnect the harness connector of the ECM.
  2. Probe the ground circuits with a test lamp that is connected to B+. The test lamp should illuminate.
    • If the test lamp does not illuminate, then test the ground circuit for an open/high resistance.
  3. Test for 11-14 volts between the battery positive voltage and the ground circuits of the ECM.
    • If not within the specified range, test the battery positive voltage circuits for a short to ground or an open/high resistance.
  4. If all circuits test normal, replace the ECM.